Thallium perfusion and myocardial hypertrophy in transplanted heart recipients with normal or near-normal coronary arteriograms

In patients with hypertrophic cardiomyopathy or systemic hypertension,exercise thallium perfusion defects have been observed but withoutsignificant angiographic stenoses. Hypertension and myocardialhypertrophy are common in transplanted heart recipients, andthe aim of this study was to determine if exercise thalliumscintigraphy false-positives are frequent in transplanted heartrecipients. Thirty-four transplanted heart recipients were evaluated byexercise thallium single emission computed tomography and subsequentlyhad a normal or near normal coronary arteriogram. At the timeof the exercise, the patients (28 men and six women) had a meanage of 48.9 ± 12 years and 29 had been previously treatedfor systemic hypertension. The mean duration between transplantationand the exercise test was 31.6 ± 13 months. In all patientsleft ventricular mass was obtained by echocardiography within3 months of thallium 201 SPECT and was 130g. m^–2 in ninemales and 110 g. m^–2 in four females. M-mode septal+posteriorend-diastolic thickness was >23 mm in 14 patients, all ofwhom had been previously treated for systemic hypertension.These patients were older and endured a longer period duringwhich the heart was kept cold but ischaemic before being grafted(‘cold ischaemia’) but a shorter exercise durationthan patients without left ventricular hypertrophy. During exercisetesting, 26 of 34 patients achieved at least 80% of their maximalpredicted heart rate and two developed significant ECG changes.Exercise and 4 h redistribution thallium perfusions were normalin 33 patients, but one patient with a left ventricular mass= 100 g. m^–2 had a persistent apical defect. We conclude that in transplanted heart recipients with normalor near normal coronary arteriograms, myocardial perfusion evaluatedwith exercise thallium 201 SPECT is usually normal despite ahigh frequency of myocardial hypertrophy.